1. Field of Invention:
This invention relates generally to blind fasteners of the toggle bolt type which are insertable in a hole drilled in a hollow wall, and more particularly to a toggle bolt assembly including means acting to prevent rotation of the toggle in the course of installation when the bolt is turned to axially advance the toggle into engagement with the inner surface of the wall to fasten the assembly thereon, and acting after the toggle engages the inner surface to prevent it and the bolt from subsequently turning as a result of vibratory forces.
2. Prior Art:
Blind fasteners of the toggle bolt type are commonly used to secure fixtures and other objects against the outer surface of a hollow wall formed of masonry, tile, cinder block, plaster or fiber board, or any other plate or panel capable of supporting a load.
As used herein, the term "toggle bolt" refers to a blind fastener having a collapsible toggle threadably received on the shank of a bolt whereby when the bolt is passed through a hole in a wall, the toggle is then collapsed to permit such passage; and when emerging from the hole, the toggle resumes its non-collapsed form to effect a fastening action. By a collapsible toggle is meant any holding element that is foldable, bendable, compressible or otherwise changeable in form to assume in the collapsed state reduced dimensions which permit its passage through a hole. Hence, while in this application there is illustrated by way of example a toggle formed by a pair of foldable wings, it is to be understood that the invention is applicable to other forms of collapsible toggles.
The term "wall" as used herein is intended to include any panel, plate or other drillable substrate on which an object is to be fastened.
The most commonly known toggle bolt assembly consists of a bolt having a threaded shank on which is received a nut provided with opposed lugs or trunnions to pivotally support a pair of spring-biased wings. The wings are normally outstretched, but they fold in against the bolt when the assembly is inserted in a drilled hole in the wall, the hole diameter being large enough to accommodate the folded-in wings. Toggle bolt assemblies of this conventional type are commercially available in various sizes and weights, the gauge depending on the loads they are intended to support on a wall.
When installing a conventional toggle bolt assembly in a hollow wall to hold a fixture or other object against its outer surface, a hole is first drilled in the wall, the diameter of the hole depending on the gauge of the toggle bolt. The toggle bolt assembly is inserted through a mounting hole in the fixture and pushed into the wall hole, the wings folding in to permit such entry. The length of the bolt is greater than the combined thickness of the fixture, the wall and the folded-in toggle wings. Hence, the wings pivoted on the nut, which initially are near the end of the bolt, resume their outstretched state when the bolt is fully inserted. The outstretched wings are thus displaced a substantial distance from the inner surface of the wall. The extent of this displacement depends on the length of the bolt relative to said combined thickness.
It is not at this point possible to tighten the wall-inserted toggle bolt; for should one turn the bolt with a screw driver, the wings, which are unrestrained, will turn with the bolt and the trunnion nut will not advance on the threaded shank of the bolt toward the inner surface of the wall. In order, therefore, to effect tightening with a conventional toggle bolt assembly, the installer must pull the fixture away from the wall to bring the outstretched wings into engagement with the inner surface of the wall and thereby resist a turning action. In this way, the bolt can be turned with a screw driver without at the same time turning the wings, and the nut will then advance on the threaded shank to effect tightening of the toggle bolt assembly.
In practice, the need to manually pull the fixture away from the wall in order to tighten the toggle bolt will in many instances present serious difficulties. For example, if panels of insulation material are to be fastened to a hollow roof by means of roofing plates, the installer for each such plate must insert the toggle bolt through a mounting hole in the plate and thread the shank of the bolt into the trunnion nut. A hole in the insulation panel and a hole in the roof are then made. The bolt carrying the toggle wings is inserted through the panel and roof holes; and the wings then assume their outstretched state at a position displaced from the inner surface of the roof.
In order to now tighten the anchor bolt, the installer must place his fingers beneath the roofing plate so as to pull the roofing plate away from the insulation panel lying on the roof until the wings then engage the inner surface of the roof, thereby preventing rotation of the wings to permit tightening of the toggle bolt.
Most professional installers now use electric screw drivers which to be rendered operative must be pressed against the head of the bolt. This presents no difficulty when the bolt head lies against a stable substrate. But if the head of the bolt lies against a roofing plate being held in one hand by the installer while his other hand grasps the electric screw driver, the inherent instability of the situation makes installations very difficult and sometimes dangerous.
One must bear in mind that a professional installer is required in the case of a typical roof installation to put in thousands of toggle bolts, and that with conventional toggle bolts, the need to pull up the roofing plate in order to tighten the bolt not only adds significantly to the time it takes to make the installation, but also increases the risk of crushed fingers or other mishaps.
Moreover, in a roof installation in which the insulation panels are secured by toggle bolts, the toggle bolts are vertically disposed; and since the exposed roof is subject to vibratory and compressive forces, this causes the toggle wings to actually unscrew to a point where the wings will fall off the screw, thereby leaving the insulation panels unsecured. As a consequence, the panels may be blown off the roof in a high wind producing a strong updraft.
Thus, the two problems of greatest concern which are encountered with conventional toggle bolt assemblies are the problem of toggle head rotation as the bolt is turned to bring the head into engagement with the inner surface of the wall and the problem of post installation loosening of the toggle bolt as a result of vibratory and other forces which cause reverse turning of the head on the bolt.
My above-identified related patent applications are addressed to both problems and provide solutions thereto. In these related applications there are disclosed a non-rotating toggle bolt assembly adapted to fasten a fixture or other object to a hollow wall, which assembly, after insertion in a hole drilled in the wall, may be tightened by a torque tool, such as a screw driver, without the need to pull the fixture away from the wall, thereby making the installation procedure faster and safer. The toggle bolt assembly includes a long tail coupled to the toggle head that acts to prevent rotation of the head in the course of installation when the bolt or screw is turned in to advance the toggle head to tighten the anchor bolt on the wall, and which also includes a short tail to prevent vibration or other forces from loosening the assembly after such installation.
These long and short tails are preferably made of metal wire and include a coupling loop or other means to link the tails to the trunnion nut. Hence, an assembly procedure is required to couple the tails to toggle bolts. This procedure is time consuming and difficult to carry out.
The following patents which deal with various forms of toggle bolts are of background interest:
Pleister: U.S. Pat. No. 2,061,634 PA0 Gelpcke: U.S. Pat. No. 2,398,220 PA0 Shamah: U.S. Pat. No. 4,286,497 PA0 Apelzweig: U.S. Pat. No. 2,998,743 PA0 Gelpcke: U.S. Pat. No. 2,567,372 PA0 Zifferer: U.S. Pat. No. 1,228,512 PA0 Goewey: U.S. Pat. No. 1,373,188 PA0 Brenizer: U.S. Pat. No. 1,600,034 PA0 Karitzky: U.S. Pat. No. 2,616,327 PA0 Topf: U.S. Pat. No. 3,302,508 PA0 Vaillancourt: U.S. Pat. No. 3,389,631 PA0 Forsberg: U.S. Pat. No. 3,513,746 PA0 Roberson: U.S. Pat. No. 4,079,655 PA0 Shamah: U.S. Pat. No. 4,286,497 PA0 Schrandolph: U.S. Pat. No. 1,237,386 (Fed. Rep. Ger.)